Methods of adjusting the power of an intraocular lens

ABSTRACT

An accommodating intraocular lens is provided, in which optical parameters are altered in-situ using forces applied by the ciliary muscles, and in which a lens body carries an actuator separating two fluid-filled chambers having either the same index of diffraction or different indices of refraction. The actuator causes the relative volumes of fluid within an optic element of the lens to change, thereby altering the optical power of the lens.

REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. applicationSer. No. 10/734,514, filed on Dec. 12, 2003, which claims the benefit ofU.S. provisional application No. 60/433,046, filed on Dec. 12, 2002, thedisclosures of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to intraocular lenses (“IOLs”) havingoptical parameters that are changeable in-situ. More particularly, theinvention has applications in IOLs for in-capsule implantation forcataract patients, wherein forces applied by the ciliary muscles in theeye induce movement of fluid media within the interior of the IOL,thereby altering an optical power of the lens to provide accommodation.

BACKGROUND OF THE INVENTION

Cataracts are a major cause of blindness in the world and the mostprevalent ocular disease. Visual disability from cataracts accounts formore than 8 million physician office visits per year. When thedisability from cataracts affects or alters an individual's activitiesof daily living, surgical lens removal with intraocular lens (IOL)implantation is the preferred method of treating the functionallimitations. In the United States, about 2.5 million cataract surgicalprocedures are performed annually, making it the most common surgery forAmericans over the age of 65. About 97 percent of cataract surgerypatients receive intraocular lens implants, with the annual costs forcataract surgery and associated care in the United States being upwardsof $4 billion.

A cataract is any opacity of a patient's lens, whether it is a localizedopacity or a diffuse general loss of transparency. To be clinicallysignificant, however, the cataract must cause a significant reduction invisual acuity or a functional impairment. A cataract occurs as a resultof aging or secondary to hereditary factors, trauma, inflammation,metabolic or nutritional disorders, or radiation. Age related cataractconditions are the most common.

In treating a cataract, the surgeon removes the crystalline lens matrixfrom the lens capsule and replaces it with an intraocular lens (“IOL”)implant. The typical IOL provides a selected focal length that allowsthe patient to have fairly good distance vision. Since the lens can nolonger accommodate, however, the patient typically needs glasses forreading.

More specifically, the imaging properties of the human eye arefacilitated by several optical interfaces. A healthy youthful human eyehas a total power of approximately 59 diopters, with the anteriorsurface of the cornea (e.g. the exterior surface, including the tearlayer) providing about 48 diopters of power, while the posterior surfaceprovides about −4 diopters. The crystalline lens, which is situatedposterior of the pupil in a transparent elastic capsule supported by theciliary muscles, provides about 15 diopters of power, and also performsthe critical function of focusing images upon the retina. This focusingability, referred to as “accommodation,” enables imaging of objects atvarious distances.

The power of the lens in a youthful eye can be adjusted from 15 dioptersto about 29 diopters by adjusting the shape of the lens from amoderately convex shape to a highly convex shape. The mechanismgenerally accepted to cause this adjustment is that ciliary musclessupporting the capsule (and the lens contained therein), move between arelaxed state (corresponding to the moderately convex shape) to acontracted state (corresponding to the highly convex shape). Because thelens itself is composed of viscous, gelatinous transparent fibers,arranged in an “onion-like” layered structure, forces applied to thecapsule by the ciliary muscles cause the lens to change shape.

Isolated from the eye, the relaxed capsule and lens take on a sphericalshape. Within the eye, however, the capsule is connected around itscircumference by approximately 70 tiny ligament fibers to the ciliarymuscles, which in turn are attached to an inner surface of the eyeball.The ciliary muscles that support the lens and capsule therefore arebelieved to act in a sphincter muscular mode. Accordingly, when theciliary muscles are relaxed, the capsule and lens are pulled about thecircumference to a larger diameter, thereby flattening the lens, whereaswhen the ciliary muscles are contracted the lens and capsule relaxsomewhat and assume a smaller diameter that approaches a more sphericalshape. This mechanism, called the “ciliary process” increases thediopter power of the lens.

As noted above, the youthful eye has approximately 14 diopters ofaccommodation. As a person ages, the lens hardens and becomes lesselastic, so that by about age 45-50, accommodation is reduced to about 2diopters. At a later age the lens may be considered to benon-accommodating, a condition know as “presbyopia”. Because the imagingdistance is fixed, presbyopia typically entails the need for bi-focalsto facilitate near and far vision.

Apart from age-related loss of accommodation ability, such loss isinnate to the placement of IOLs for the treatment of cataracts. IOLs aregenerally single element lenses made from a suitable polymer material,such as acrylics or silicones. After placement, accommodation is nolonger possible, although this ability is typically already lost forpersons receiving an IOL. There is significant need to provide foraccommodation in IOL products so that IOL recipients will haveaccommodating ability.

Although previously known workers in the field of accommodating IOLshave made some progress, the relative complexity of the methods andapparatus developed to date have prevented widespread commercializationof such devices. Previously known these devices have proved to complexto be practical to construct or have achieved only limited success, dueto the inability to provide accommodation of more than 1-2 diopters.

U.S. Pat. No. 5,443,506 to Garabet describes an accommodatingfluid-filled lens wherein electrical potentials generated by contractionof the ciliary muscles cause changes in the index of refraction of fluidcarried within a central optic portion. U.S. Pat. No. 4,816,031 to Pfoffdiscloses an IOL with a hard PMMA lens separated by a single chamberfrom a flexible thin lens layer that uses microfluid pumps to vary avolume of fluid between the PMMA lens portion and the thin layer portionand provide accommodation. U.S. Pat. No. 4,932,966 to Christie et al.discloses an intraocular lens comprising a thin flexible layer sealedalong its periphery to a support layer, wherein forces applied to fluidreservoirs in the haptics vary a volume of fluid between the pluralityof layers to provide accommodation.

Although fluid-actuated mechanisms such as described in theaforementioned patents have been investigated, accommodating lensescurrently nearing commercialization, such as developed by Eyeonics, Inc.(formerly C&C Vision, Inc.) of Aliso Viejo, Calif., rely ciliary musclecontraction of the IOL haptics to move the optic towards or away fromthe retina to adjust the focus of the device.

In view of the foregoing, it would be desirable to provide apparatus andmethods that restore appropriate optical focusing power action to thehuman eye.

It further would be desirable to provide methods and apparatus wherein adynamic lens surface may be effectively manipulated by the ciliarymuscular mechanisms within the eye.

It still further would be desirable to provide methods and apparatusthat utilize pressure applied by the accommodating muscular action toobtain mechanical deviation of an optical surface of the IOL. Inparticular, it would be desirable to provide an IOL in which muscularpressure may be applied through one or more actuators to obtain amechanical advantage.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention toprovide apparatus and methods that restore appropriate optical focusingpower action to the human eye.

It is a further object of this invention to provide methods andapparatus wherein a dynamic lens surface may be effectively manipulatedby the ciliary muscular mechanisms within the eye.

It is another object of the present invention to provide methods andapparatus that utilize pressure applied by the accommodating muscularaction to obtain mechanical deviation of an optical surface of the IOL.

It is a further object of this invention to provide methods andapparatus for applying muscular pressure, through one or more actuators,to obtain a mechanical advantage in altering the optical parameters ofone of more surfaces of the IOL.

These and other objects of the present invention are accomplished byproviding a lens in which force exerted on a fluid reservoir by theciliary process is applied to a moveable optical surface through anactuator whose area is the same as or smaller than the area of theoptical surface. In this manner, the optical surface is made to movethrough a deflection that is more pronounced than would be otherwisepossible. In addition, the force exerted by the ciliary process upon theouter surface of the IOL may be oriented in a direction optimal for themotion of the optical surface.

In accordance with the principles of the invention, a lens is providedcomprising an optic element forming a housing and having an actuatorthat divides the housing into first and second fluid chambers. The firstand second fluid chambers are filled with first and second fluids,respectively, having either the same index of defraction or differentindices of refraction. The optical parameters of the lens are altered byvarying the amounts of first and second fluids in the first and secondchambers. In a first embodiment the actuator comprises a flexibletransparent layer operated on directly by movement of fluid from areservoir; in a second embodiment the actuator comprises one or moreextensible cells that act to deflect a flexible transparent layer.

In accordance with another aspect of the invention, a reservoircontaining one of the first or second fluids is disposed in a haptic ofthe IOL, so that forces applied to the haptic by the ciliary process aretransmitted via the fluid to deform the flexible layer. In alternativeembodiments the reservoirs may be located in a non-optic portion of thelens and actuated by compressive or torsional forces applied by theciliary muscles through the haptics.

Alternatively, or in addition, fulcrum points may be disposed within theoptic element to facilitate deflection of the flexible layer, therebyproviding a multiplying effect of the forces applied by the ciliaryprocess.

Methods of using the lens of the present invention also are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments, in which:

FIG. 1 is a sectional side view of a human eye;

FIGS. 2A and 2B are, respectively, detailed sectional side views of thelens and supporting structures of FIG. 1 illustrating relaxed andcontracted states of the ciliary muscles;

FIGS. 3A and 3B are, respectively, an exploded perspective and sidesectional view taken along line 3B-3B of an exemplary embodiment of anaccommodating intraocular lens constructed in accordance with theprinciples of the present invention;

FIGS. 4A and 4B are, respectively, an exploded perspective and sidesectional view taken along line 4B-4B of an alternative embodiment of anaccommodating intraocular lens of the present invention;

FIG. 5 is a side sectional view of an alternative embodiment of theaccommodating IOL similar to that of FIGS. 4A and 4B, depicting the useof an annular fulcrum;

FIGS. 6A and 6B are, respectively, an exploded perspective and sidesectional view taken along line 6B-6B of another alternative embodimentof an accommodating intraocular lens of the present invention;

FIGS. 7A-7C are schematic views of illustrating the use of fulcrumpoints to facilitate deflection of an optical surface in accordance withthe principles of the present invention;

FIG. 8 is a side-sectional view of another illustrative embodiment inwhich inflow and outflow pathways connect the optic element to a fluidreservoir;

FIGS. 9A and 9B are, respectively, a plan view, partly in section, and aside-sectional view of another embodiment of the lens of the presentinvention in which the reservoir is designed to equalize forces appliedby the ciliary muscles;

FIGS. 10A and 10B are, respectively, an exploded perspective view and aside-sectional view of another alternative embodiment of the lens of thepresent invention; and

FIG. 11 is a plan view of an alternative haptic arrangement for a lensof type shown in FIGS. 10.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to an in-situ accommodatingintraocular lens system. In accordance with the principles of thepresent invention, methods and apparatus are provided wherein a lens hasan optic element comprising a substrate and an actuator that divides theinterior of the housing into two or more fluid-filled chambers. Thefluids filling the chambers may have the same or different indices ofrefraction. The optical power of the lens is altered by changing therelative amounts of fluids in the chambers, thereby changing thecurvature of one of the chambers and the refractive path of lightpassing through the optic element.

Referring to FIGS. 1 and 2, the structure and operation of a human eyeare first described as context for the present invention. Eye 10includes cornea 11 pupil 12, ciliary muscles 13, ligament fibers 14,capsule 15, lens 16 and retina 17. Natural lens 16 is composed ofviscous, gelatinous transparent fibers, arranged in an “onion-like”layered structure, and is disposed in transparent elastic capsule 15.Capsule 15 is joined by ligament fibers 14 around its circumference tociliary muscles 13, which are in turn attached to the inner surface ofeye 10.

Isolated from the eye, the relaxed capsule and lens takes on a sphericalshape. However, as described hereinabove, when suspended within the eyeby ligament fibers 14, capsule 15 moves between a moderately convexshape (when the ciliary muscles are relaxed) to a highly convex shape(when the ciliary muscles are contracted). As depicted in FIG. 2A, whenciliary muscles 13 relax, capsule 15 and lens 16 are pulled about thecircumference, thereby flattening the lens. As depicted in FIG. 2B, whenciliary muscles 13 contract, capsule 15 and lens 16 relax somewhat, thusallowing the lens and capsule to assume a more spherical shape, and thusincreasing the diopter power of the lens.

As discussed hereinabove, accommodating lenses currently nearingcommercialization, such as the Crystalens device under development byEyeonics, Inc., Aliso Viejo, Calif., typically involve convertingdiametral movements of the ciliary muscle into forward and backwardmovement of the optic portion of the IOL relative to the retina. Thisapproach is thought to be required because, following extraction of acataract-effected lens, the capsular bag is very loose, and the ligamentfibers that couple the capsule to the ciliary muscles are no longer intension. Devices such as the Crystalens thus do not employ the naturalaccommodation mechanisms described above, but instead rely directly onradially inward compressive forces applied by the ciliary muscle to thehaptics of the IOL.

In accordance with principles of the present invention, radiallycompressive forces applied to the haptics of the IOL are employed toprovide accommodation by deflecting a flexible transparent layer thatseparates two fluids preferably having different indices of refraction.This deflection causes a variation in the optical path of light passingthrough the lens, thus altering its optical parameters.

Referring now to FIGS. 3A and 3B, a first illustrative embodiment of anaccommodating IOL of the present invention is described. IOL 20preferably comprises substrate 21, flexible layer 22 and anteriorelement 23, which may be assembled in a sandwiched configuration,depicted in FIG. 3B.

Substrate 21 preferably comprises a sturdy transparent polymer andincludes posterior lens 24, haptics 25, lower chamber 26, reservoirs 27,passageways 28 and relief chambers 29. Lower chamber 26 communicateswith reservoirs 27 disposed on the ends of haptics 25 via passageways28. Lower chamber 26, reservoirs 27 and passageways 28 are filled withtransparent fluid 30, such as silicone. The outwardly directed surfacesof haptics 25 preferably comprise a resilient elastic material thatpermits force applied to those surfaces by the ciliary muscles to causefluid to move from reservoirs 27 through passageways 28 into lowerchamber 26.

Anterior element 23 preferably comprises a rigid transparent material,and includes anterior lens 31, and relief reservoirs 32. The interiorsurface of anterior element 23 is convex and forms upper chamber 33,which accommodates upward motion of flexible transparent layer 22, asdescribed hereinbelow. Relief reservoirs 32 are disposed in alignmentwith relief chambers 29 in substrate 21, outside the optical path ofanterior lens 31. Upper chamber 33 communicates with relief reservoirs32 via passageways 34, and is filled with transparent fluid 35, such assilicone. Preferably, transparent fluid 30 in lower chamber 26 has adifferent index of refraction than transparent fluid 35 in upper chamber33.

Flexible transparent layer 22 divides upper chamber 33 of anteriorelement 23 from lower chamber 26 of substrate 21 and acts as an actuatorin redistributing the relative volumes of fluid in the upper and lowerchambers. Ends 36 of flexible transparent layer also separate reliefreservoirs 32 in anterior element 23 from relief chambers 29 insubstrate 21. Because relief chambers 29 are empty, they permit excessfluid entering the relief reservoirs 32 to cause the layer to reversiblybulge into the relief chambers when flexible transparent layer isdeflected upward.

When assembled as shown in FIG. 3B and implanted into the empty capsuleof a cataract patient, compressive forces applied by the ciliary musclescause fluid 30 to move from reservoirs 27 into lower chamber 26, therebycausing flexible transparent layer 22 to deflect upward, as shown indotted line. Upward motion of layer 22 causes excess fluid in upperchamber 33 to move through passageways 34 into relief reservoirs.Because relief chambers 29 in substrate 21 are not fluid-filled, theypermit layer 22 to bulge downward into the relief chambers.

In accordance with the principles of the present invention, movement oflayer 22, and the accompanying displacement of a volume of fluid 35 witha volume of fluid 30 of a different index of fraction, changes theoptical parameters of the lens, thereby moving the focus of the lensfrom near to far or vice-versa. Posterior lens 24 also provides opticalpower, and also optical index dispersion so as to optimize aberrationcharacteristics, including wave aberration of all order, or chromaticaberration.

When the ciliary muscles relax, layer 22 resiliently contracts to itsoriginal position, forcing excess fluid 30 from lower chamber back intoreservoirs 27 via passageways. In addition, as the pressure in upperchamber 33 is reduced, fluid 35 passes out of relief reservoirs 32 viapassageways 34 and into upper chamber 33, thereby relieving bulging oflayer 22 into relief chambers 29.

Referring now to FIGS. 4A and 4B, another illustrative embodiment of anaccommodating IOL of the present invention constructed in accordancewith the principles of the present invention is described. IOL 40 issimilar in construction to IOL 20 of FIGS. 3, but has two interfaces toalter the power of the lens responsive to fluid movement. Morespecifically, IOL 40 comprises substrate 41, flexible layer 42, anteriorelement 43, flexible layer 44 and posterior element 45. All of thesecomponents are assembled in a sandwiched configuration, as depicted inFIG. 4B.

Substrate 41 preferably comprises a sturdy transparent polymer andincludes haptics 46, central chamber 47, reservoirs 48, passageways 49and relief chambers 50 formed in each of upper surface 51 and lowersurface 52. Central chamber 47 communicates with reservoirs 48 disposedon the ends of haptics 46 via passageways 49. Central chamber 47,reservoirs 48 and passageways 49 are filled with transparent fluid 54,such as silicone. The outwardly directed surfaces of haptics 46preferably comprise a resilient elastic material that permits forceapplied to those surfaces by the ciliary muscles to cause fluid to movefrom reservoirs 48 through passageways 49 into central chamber 47.

Anterior element 43 preferably comprises a rigid transparent material,and includes anterior lens 55, and relief reservoirs 56. The interiorsurface of anterior element 43 is convex and forms upper chamber 57,which accommodates upward motion of flexible transparent layer 42, asdescribed hereinbelow. Relief reservoirs 56 are disposed in alignmentwith relief chambers 50 in substrate 41, outside the optical path ofanterior lens 43. Upper chamber 57 communicates with relief reservoirs56 via passageways 58, and is filled with transparent fluid 59, such assilicone. Preferably, transparent fluid 54 in central chamber 47 has adifferent index of refraction than transparent fluid 59 in upper chamber57.

Posterior element 45 is similar in construction to anterior element 43,and preferably comprises a rigid transparent material. Posterior element45 includes posterior lens 60 and relief reservoirs 61. The interiorsurface of posterior element 45 is convex upward and forms lower chamber62, which accommodates downward motion of flexible transparent layer 44.Relief reservoirs 61 are disposed in alignment with relief chambersformed in the lower surface of substrate 41, outside the optical path ofposterior lens 45. Lower chamber 62 communicates with relief reservoirs61 via passageways 64, and is filled with transparent fluid 65, whichmay be the same as fluid 59 in upper chamber 57. Preferably, transparentfluid 54 in central chamber 47 has a different index of refraction thantransparent fluid 65 in lower chamber 62.

Flexible transparent layer 42 separates upper chamber 57 of anteriorelement 43 from central chamber 47 of substrate 41, while flexibletransparent layer 44 separates lower chamber 62 from central chamber 47.As described below, layers 42 and 44 act as actuators for altering therelative volumes of fluids in the chambers, and thus the optical powerof the lens. The ends of flexible transparent layer 42 separate reliefreservoirs 56 in anterior element 43 from relief chambers 50 in theupper surface of substrate 41. Likewise, the ends of flexibletransparent layer 44 separate relief reservoirs 61 in posterior element45 from the relief chambers in the lower surface of substrate 41.Because the relief chambers are empty, they permit excess fluid enteringthe relief reservoirs 56 and 61 to cause layers 42 and 44 to reversiblybulge into the relief chambers when flexible transparent layers 42 and44 are deflected outward from central chamber 47.

When assembled as shown in FIG. 4B and implanted into the empty capsuleof a cataract patient, compressive forces applied by the ciliary musclescause fluid 54 to move from reservoirs 48 into central chamber 47,thereby causing flexible transparent layers 42 and 44 to deflectoutward. Upward motion of layer 42 and downward motion of layer 44causes excess fluid in upper and lower chambers 57 and 62 into therespective relief reservoirs 56 and 61. Because the corresponding reliefchambers in substrate 41 are not fluid-filled, they permit layers 42 and44 to bulge into the relief chambers. Movement of layers 42 and 44, andthe accompanying displacement of volumes of fluid 59 and 65 with volumesof fluid 54 of a different index of fraction, changes the opticalparameters of the lens, thereby moving the focus of the lens from nearto far or vice-versa.

When the ciliary muscles relax, each of layers 42 and 44 resilientlycontracts to its original position, forcing excess fluid from centralchamber 47 back into reservoirs 49. In addition, as pressure in upperand lower chambers 57 and 62 is reduced, fluids 59 and 65 return fromrelief reservoirs 56 and 61 into the upper and lower chambers,respectively.

Referring now to FIG. 5, an alternative embodiment of an accommodatingIOL of the invention, similar in design to the embodiment of FIGS. 4 isdescribed. IOL 70 comprises substrate 71, flexible layers 72 and 73, andanterior and posterior elements 74 and 75, assembled in a sandwichedconfiguration.

Substrate 71 is similar in construction to substrate 41 of FIGS. 4, andcomprises haptics 76, central chamber 77, reservoirs 78, passageways 79and relief chambers formed in each of its upper and lower surfaces,arranged as described for the embodiment of FIGS. 4. With thisarrangement, force applied to the outer surfaces of haptics 76 by theciliary muscles cause fluid to move from reservoirs 78 throughpassageways 79 into central chamber 77.

Anterior element 74 preferably comprises a rigid transparent material,and anterior lens 81, relief reservoirs (arranged as in the embodimentof FIGS. 4), and annular fulcrum 82. The interior surface of anteriorelement 74 is convex and forms fluid-filled upper chamber 83, whichaccommodates upward motion of flexible layer 72, as describedhereinbelow. Relief reservoirs are disposed in alignment with reliefchambers in substrate 71, outside the optical path of anterior lens 74,and act to relieve excess pressure in the upper chamber when flexiblelayer 72 deflects upward. As described for the embodiment of FIGS. 4,upper chamber 83 contains a fluid having a different index of refractionthan the fluid in central chamber 77. Posterior element 75 is similar inconstruction to anterior element 74, and preferably also includesannular fulcrum 84 disposed in fluid-filled lower chamber 85.

Flexible transparent layer 72 separates upper chamber 83 of anteriorelement 74 from central chamber 77 of substrate 41, while flexibletransparent layer 73 separates lower chamber 85 from central chamber 77.Layers 72 and 73 preferably comprise a resilient flexible material thatflexes against annular fulcrums 82 and 84 when fluid is moved intocentral chamber 77 by forces applied to reservoirs 78.

In the embodiment of FIG. 5, annular fulcrum 82 illustratively comprisesan annular ring extending inward from the interior surface of anteriorelement 74 to contact flexible layer 72, and may include apertures topermit transparent fluid contained in upper chamber 83 to move freelywithin the chamber. Annular fulcrum 84 disposed in lower chamber 85comprises a corresponding structure that contacts flexible layer 73.Fulcrums 82 and 84 fix the surfaces of layers 72 and 73 to optimize theefficiency and effectiveness of changing the optical power of layers 72and 73 using the available flow of fluid.

As will be appreciated, the mechanical advantage obtained by fulcrums 82and 84, and the degree of deflection imposed upon layers 72 and 73 isdependent upon the distance of the fulcrum contact point from theoptical axis of the lens. In addition, while illustratively described asannular rings, fulcrums 82 and 84 may comprise other suitable shapes,such as discrete pegs or cones.

Operation of the embodiment of FIG. 5 is similar to that of theembodiment of FIGS. 4, except that fulcrums 82 and 84 control deflectionof layers 72 and 73. When implanted into the empty capsule of a cataractpatient, compressive forces applied by the ciliary muscles cause fluidto move from reservoirs 78 into central chamber 77, thereby causinglayers 72 and 73 to deflect outward.

Because outward motion of layers 72 and 73 is fixed by the points ofcontact with fulcrums 82 and 84, layers 72 and 73 may assume differentdeflection patterns (illustrated in dotted line in FIG. 5) than for theunconstrained layers in the embodiment of FIGS. 4. Deflection of layers72 and 73, and the accompanying displacement of volumes of fluid inupper and lower chambers 83 and 85 with corresponding volumes of fluidof a different index of fraction in central chamber 77, changes theoptical parameters of the lens, thereby moving the focus of the lensfrom near to far or vice-versa.

When the ciliary muscles relax, each of layers 72 and 73 returns to itsoriginal position, thereby forcing excess fluid from central chamber 77back into reservoirs 78. In addition, as pressure in upper and lowerchambers 83 and 85 is reduced, fluid returns from the relief reservoirsinto the upper and lower chambers respectively, as described for thelens of FIGS. 4.

Referring now to FIGS. 6A and 6B, another alternative embodiment of anaccommodating IOL of the present invention is described, in which aflexible layer is deflected using extensible cells that have a smallerarea than the layer itself. IOL 90 comprises substrate 91, actuatorelement 92, flexible layer 93 and anterior element 94, which may beassembled in a sandwiched configuration, FIG. 6B.

Substrate 91 preferably comprises a sturdy transparent polymer andincludes posterior lens 95, haptics 96, lower chamber 97, reservoirs 98,passageways 99 and lower relief reservoirs 100. Lower chamber 97communicates with reservoirs 98 disposed on the ends of haptics 96 viapassageways 99. Lower chamber 97, reservoirs 98, passageways 99 andlower relief reservoirs 100 are filled with transparent fluid 101. Theoutwardly directed surfaces of haptics 96 comprise a resilient elasticmaterial that permits force applied to those surfaces by the ciliarymuscles to cause fluid to move from reservoirs 98 through passageways 99into lower chamber 99.

Actuator element 92 comprises disk-shaped member 102 having a pluralityof cells 103 extending upwardly from its upper surface. Each cell 103illustratively comprises an annular sidewall 104 and top 105. Therelative thickness of member 102 and sidewalls 104 and tops 105 areselected so that when pressurized fluid is introduced into lower chamber97, tops 105 of cells 103 extend axially upward. Illustratively, cells103 are arranged in a ring at a predetermined radius from the opticalaxis of lens 90, although more or fewer cells 103 may be employed, andthen location selected to enhance deflection of layer 93, as describedhereinbelow.

Anterior element 94 preferably comprises a rigid transparent material,and includes anterior lens 106, and upper relief reservoirs 107. Theinterior surface of anterior element 94 is convex and forms upperchamber 108, which accommodates upward motion of flexible layer 93, asdescribed hereinbelow. Upper relief reservoirs 107 are disposed inalignment with lower relief chambers 100 in substrate 91, outside theoptical path of anterior lens 94. Upper chamber 108 communicates withupper relief reservoirs 107 via passageways 109, and is filled withtransparent fluid 110.

Flexible layer 93 is affixed around its circumference to substrate 91and is disposed in contact with tops 105 of cells 103. Transparent fluid111 is contained within space 112 between the upper surface of actuatorelement 92 and lower surface of layer 93. Lower relief reservoirs 100communicate with space 112 via passageways 113 disposed in substrate 91.A portion of layer 93 divides upper relief reservoirs 107 from lowerrelief reservoirs 100, for purposes to be described hereinafter. Fluid111 disposed in space 112 preferably has the same index of refraction asfluid 101 in lower chamber 97, and a different index of refraction thanfluid 110 contained in upper chamber 108.

When assembled as shown in FIG. 6B and implanted into the empty capsuleof a cataract patient, compressive forces applied by the ciliary musclescause fluid 101 to move from reservoirs 98 into lower chamber 97,thereby causing tops 105 of cells 103 to extend axially upward. Upwardmovement of tops 105 of cells 103 in turn causes layer 93 to deflectupward and displace fluid 110 in upper chamber 108. Fluid displaced fromupper chamber 108 flows into upper relief reservoirs 107 via passageways109.

Simultaneously, because lower relief reservoirs 100 communicate withspace 112, fluid 111 is drawn from lower relief reservoirs as layer 93is deflected upward by cells 103. Consequently, the portions of layer 93that divide upper relief reservoirs 107 from lower relief reservoirs 100serve as diaphragms that permit fluid to be simultaneously displacedinto one reservoir and withdrawn from the other. This enables fluids 110and 111 to pass freely in and out of the optical space in order tobalance relative volumes of fluid, the total volume of fluids 110 and111 remaining constant.

In accordance with the principles of the present invention, movement oflayer 93, and the accompanying displacement of volumes of fluid 110 inupper chamber 108 with a corresponding volume of fluid 111 of adifferent index of fraction in space 112, changes the optical parametersof the lens, thereby moving the focus of the lens from near to far orvice-versa. Posterior lens 95, which in this case comprises a solidmaterial, also provides additional optical power. Posterior lens 95 alsomay provide optical index dispersion so as to optimize aberrationcharacteristics, including wave aberration of all order, or chromaticaberration.

When the ciliary muscles relax, tops 105 of cells 103 contract, andlayer 93 resiliently contracts to its original position. This in turnforces excess fluid 111 in space 112 back into lower relief reservoirs100. In addition, as the pressure in upper chamber 108 is reduced, fluid110 is drawn out of upper relief reservoirs 107 and into upper chamber108.

In the embodiment of FIGS. 6, fluid 101 is forced into cell 103 byciliary forces acting on the surface of reservoir 98, so that theactuator works in a direction parallel to the optical axis of the lens.As will be appreciated, actuator element 92 must be index matched tofluid 101, which moves with cells 103, as well as fluid 111 thatsurrounds cells 103 in space 112. Also in the embodiment of FIGS. 6,posterior lens 95 is formed from the same material as substrate 91.Alternatively, posterior lens 95 may comprise a different material thansubstrate 91, having a shape and optical parameters chosen to optimizethe optical performance of the lens system.

In accordance with another aspect of the present invention, cells 103 ofthe embodiment of FIGS. 6 act not only to deflect layer 93, but alsoserve as fulcrum contact points, in a manner analogous to the annularfulcrum 82 of the embodiment of FIG. 5.

Referring now to FIGS. 7A-7C, the effect of location of the fulcrum,whether a solid point of contact (as in FIG. 5) or point of contact of acell (as in FIGS. 6) is further described. Generally, fixation withinthe optical zone of surface 120 (corresponding to the layer or flexiblelayers of the various embodiments described hereinabove), may beaccomplished in several fashions depending on the effect and efficiencyrequired of the fluid forces provided by the fluid being moved into thechamber or cell by the forces acting on the reservoirs in the IOLhaptics.

If it is desired that surface 120 assume a flatter configuration 120′that provides less optical focusing power (shown in dotted line in FIG.7A), then fixation at fulcrum point 121 would be desired. If, on theother hand, it is desired that surface 120 provide more power when theciliary muscles contract (corresponding to highly convex configuration120″, shown in dotted line in FIG. 7B), then fixation at fulcrum points122 would be desirable.

As a further alternative, to obtain most efficient use of fluid power,e.g., to obtain maximal change in optical power for a given movement ofsurface 120 (corresponding to surface configuration 120′′′ in FIG. 7C),some fixation at some intermediate fulcrum point 123 may be desired.Fulcrum point 123 also may be selected so as to minimize the change inthe volumes of the total fluid within the optical zone, therebyobviating the need for relief reservoirs to absorb excess fluid volumes.In this latter case, deflection of the flexible layer causes sufficientredistribution of the fluids within the first and second chambers toalter the power of the lens.

It additionally should be understood that by selecting the indices ofrefraction of the solid and liquid materials used in the lens of thepresent invention, it may be possible for a positive surface (i.e.,convex surface) to act as a negative lens, and vice-versa.

The dynamic response of the eye is relatively fast, but is not beyondthe ability of fluids to move in the dimensions of interests, on theorder of 5 mm or less. It may, however, be required that the fluidmotion be managed in some manner so as to avoid fatiguing the ciliarymuscles.

Referring now to FIG. 8, an exemplary arrangement is described forcontrolling fluid flows into and out of a cell, such as cell 103 of theembodiment of FIGS. 6. IOL 130 is constructed similarly to IOL 90 ofFIGS. 6, and is designated with like-primed numbers. IOL 130 differs,however, in that instead of having single passageway 99 connectingreservoir 98 to lower chamber 97, as in FIGS. 6, separate inflow channel131 and outflow channel 132 are provided, each controlled by a one-wayvalve, such as flap valves 133 and 134. In addition, inflow channel 131may have a smaller or larger cross-sectional area than outflow channel132. Alternatively, inflow and outflow channels 131 and 132 may have thesame flow area, but with more or fewer inflow channels than outflowchannels.

With respect to FIGS. 9A and 9B, a further alternative embodiment of thelens of the present invention is described. Whereas the previouslydescribed lens embodiments illustratively employ two haptics, each withits own reservoir, IOL 140 comprises single haptic 141 that surroundsthe optic element. Haptic 141 contains reservoir 142 that is coupled bychannels 143 to manifold 144. Manifold 144 serves to equalize pressuresapplied to the haptic by the ciliary muscles, and equalize the resultingfluid flows through passageways 145 to chamber 146 and thus cell 147.Cell 147 in turn controls deflection of layer 148, as in theabove-described embodiment of FIGS. 6. As described for the precedingembodiments, all surfaces and fluids are appropriately index matched.

Referring now to FIGS. 10A and 10B, a further alternative embodiment ofan accommodating lens constructed in accordance with the principles ofthe present invention is described. IOL 150 comprises substrate 151,actuator element 152 and anterior element 153, which may be assembled ina sandwiched configuration, FIG. 10B.

Substrate 151 preferably comprises a sturdy transparent polymer andincludes posterior lens 154, haptics 155, lower chamber 156, reservoirs157 and passageways 158. Lower chamber 156 communicates with reservoirs157 via passageways 158, and lower chamber 156, reservoirs 157 andpassageways 158 are filled with transparent fluid 159. Haptics 155 haveends 160 that are slidably disposed in reservoirs 157 and serve asplungers that permit compressive force applied to the haptics by theciliary muscles to cause fluid to move from reservoirs 157 throughpassageways 156 and into lower chamber 156. Haptics 155 may include coilsprings 161 or other suitable means to bias the haptics to an extendedposition that maintains engagement of the outer surfaces of the hapticswith the capsule and/or ciliary muscles.

Actuator element 152 comprises disk-shaped member 162 having a pluralityof cells 163 extending upwardly from its upper surface. Each cell 163illustratively comprises annular sidewall 164 and top 165. The relativethickness of member 162 and sidewalls 164 and tops 165 are selected sothat tops 165 are relatively more flexible than the other portions ofactuator element 152. Accordingly, when pressurized fluid is introducedinto lower chamber 156, tops 165 of cells 163 extend axially upward.Illustratively, cells 163 are arranged in a ring at a predeterminedradius from the optical axis of lens 150, although more or fewer cells163 may be employed, and their location selected to enhance deflectionof the flexible layer of anterior element 153, as described hereinbelow.

Anterior element 153 comprises flexible transparent layer 166 that formsthe anterior lens of IOL 150, and support ring 167. Flexible transparentlayer 166 assumes a convex shape when it contacts tops 165 of cells 163,and forms upper chamber 168. Because flexible transparent layer 166 canmove outward when deflected by cells 163, relief reservoirs as in theembodiment of FIGS. 6, may be omitted. Upper chamber 168 is filled withtransparent fluid 169 having an index of refraction the same as fluid159 disposed in lower chamber 156 and the interior of cells 163, andpreferably the same index of refraction as the material of transparentlayer 166. Layer 166 may have a cross-sectional thickness profile, orstiffness profile, that provides for optimal deformation when forcesfrom cells 163 are applied, so that good optical performance may beobtained throughout the deflection range.

When assembled as shown in FIG. 10B and implanted into the empty capsuleof a cataract patient, compressive forces applied by the ciliary musclescause fluid 159 to move from reservoirs 157 into lower chamber 156,thereby causing tops 165 of cells 163 to extend axially upward. Upwardmovement of tops 165 of cells 163 in turn causes flexible layer 166 ofthe anterior element to deflect upward and redistribute fluid 169contained in upper chamber 168.

In accordance with the principles of the present invention, movement offlexible layer 166, and the accompanying redistribution of fluid 169 inupper chamber 168, with a corresponding increase in the volume of fluid159 in cells 163, changes the optical parameters of the lens, therebymoving the focus of the lens from near to far or vice-versa. Posteriorlens 154, which in this case comprises a solid material, also providesadditional optical power, and also may provide optical index dispersionso as to optimize aberration characteristics.

When the ciliary muscles relax, coil springs 161 drive haptics 155radially outward, thereby drawing fluid from within cells 163 intoreservoirs 157. This in turn permits tops 165 of cells 163 to contract,and flexible layer 166 resiliently contracts to its original position.As for the previous embodiments, fluid is forced into the cells byciliary forces acting on the reservoirs through the haptics, so that theactuator works in a direction parallel to the optical axis of the lens.In addition, cells 163 of the embodiment of FIGS. 10 act not only todeflect flexible layer 166, but also serve as fulcrum contact points.

Referring to FIG. 11, another alternative embodiment of theaccommodating IOL of the present invention is described. IOL 170 issimilar in construction to IOL 150 of FIGS. 10, and includes substrate171, actuator element 172 and anterior element 173. Substrate 171includes reservoirs 174 that are coupled to lower chamber (disposedbeneath actuator element 172) via passageways 175. The lower chamber isfluidly coupled to the interior of cells 176 as described above withrespect to FIG. 10B. Anterior element 173 includes flexible transparentlayer 177 disposed in contact with the tops of cells 176, and is coupledto substrate 171 via support ring 178.

Haptics 179 are affixed to substrate 171 so that lever portions 180 ofthe haptics contact flexible walls of reservoirs 174. Haptics 179 areconfigured to engage the capsule, so that contraction of the ciliarymuscles applies a torsional force on lever portions of the haptics. Thisforce manifests as a compression of reservoirs 174, which in turn causesfluid to move from reservoirs 174 through the lower chamber and into theinteriors of cells 176. The tops of cells 176 then extend upwardly,causing flexible transparent layer 177 to deflect. As described for thepreceding embodiment of FIGS. 10, deflection of layer 177 permitsredistribution of fluid within the lens, thus altering the optical powerof the lens. When the ciliary muscles relax, lever portions 180 reducethe force applied to reservoirs 174, and the lens returns to itsunstressed condition.

While preferred illustrative embodiments of the invention are describedabove, it will be apparent to one skilled in the art that variouschanges and modifications may be made therein without departing from theinvention. The appended claims are intended to cover all such changesand modifications that fall within the true spirit and scope of theinvention.

1. A method of adjusting the power of an intraocular lens to provideaccommodation, the method comprising: providing a lens having a housing,an actuator disposed within the housing to separate the housing intofirst and second chambers disposed along the optical path of the lens, afirst volume of a first fluid having a first index of refractioncontained within the first chamber, and a second volume of a secondfluid having a second index of refraction contained within the secondchamber; and actuating the actuator to alter the first volume relativeto the second volume responsive to a contraction of a ciliary muscle,thereby changing an optical parameter of the lens.
 2. The method ofclaim 1, further comprising providing a reservoir coupled to the firstchamber, wherein actuating the actuator comprises moving an amount ofthe first fluid from the reservoir to the first chamber.
 3. The methodof claim 2, wherein the lens further comprises a haptic configured totransmit force from the ciliary muscle to the reservoir, and whereinmoving an amount of the first fluid from the reservoir to the firstchamber comprises applying a compressive force to the haptic.
 4. Themethod of claim 3, wherein providing the reservoir comprises providingthe reservoir disposed in the haptic.
 5. The method of claim 1, whereinthe lens further comprises a relief reservoir, and wherein actuating theactuator comprises moving an amount of the second fluid from the secondchamber to the relief reservoir.
 6. The method of claim 1, wherein theactuator comprises one or more extensible cells disposed in contact witha flexible transparent layer, and wherein actuating the actuatorcomprises actuating the one or more cells to deflect the flexibletransparent layer.
 7. The method of claim 6, wherein the flexibletransparent layer comprises an anterior surface of the housing having acurvature, wherein the first index of refraction is substantiallysimilar to the second index of refraction, and wherein actuating theactuator comprises actuating the one or more cells to deflect theflexible transparent layer to alter the curvature of the anteriorsurface of the housing.
 8. The method of claim 7, wherein the actuatoris provided with a third index of refraction, the third index ofrefraction being substantially equal to the first and second indices ofrefraction.
 9. The method of claim 6, wherein the lens further comprisesa reservoir coupled to the one or more extensible cells, and whereinactuating the one or more extensible cells comprises moving an amount ofa third fluid from the reservoir to an interior or the one or moreextensible cells.
 10. The method of claim 6, wherein actuating the oneor more extensible cells causes the flexible layer to deflect with theone or more extensible cells acting as a fulcrum.
 11. The method ofclaim 1, wherein the actuator comprises a flexible transparent layer,the method further comprising providing a fulcrum disposed in contactwith the flexible transparent layer, and wherein actuating the actuatorcomprises deflecting the flexible layer while maintaining a fixationpoint at the fulcrum.
 12. A method of adjusting the power of anintraocular lens to provide accommodation, the method comprising:providing a lens having a housing, an actuator disposed within thehousing to separate the housing into first and second non-communicatingchambers, a first volume of a first fluid having a first index ofrefraction contained within the first chamber, and a second volume of asecond fluid having a second index of refraction contained within thesecond chamber; and actuating the actuator to alter the first volumerelative to the second volume responsive to contraction of a ciliarymuscle, thereby changing an optical parameter of the lens.
 13. Themethod of claim 12, further comprising providing a reservoir coupled tothe first chamber, wherein actuating the actuator comprises moving anamount of the first fluid from the reservoir to the first chamber. 14.The method of claim 13, wherein providing the reservoir comprisesproviding the reservoir with controllable flow in and out of thereservoir.
 15. The method of claim 13, wherein providing the lensfurther comprises providing a haptic connected to the lens andconfigured to engage a ciliary muscle of an eye and to transmit force tothe reservoir.
 16. The method of claim 15, wherein providing thereservoir comprises providing the reservoir disposed in the haptic. 17.The method of claim 13, wherein providing the lens further comprisesproviding a relief reservoir in fluid communication with the secondchamber.
 18. The method of claim 13, wherein providing the actuatorcomprises providing the actuator with one or more extensible cells, andwherein the first volume is altered relative to the second volume bymoving an amount of a third fluid between the one or more extensiblecells and a reservoir connected to the one or more extensible cells. 19.The method of claim 12, wherein providing the housing comprisesproviding the housing with an anterior element having a flexibletransparent layer with a curvature, wherein providing the actuatorcomprises providing the actuator with one or more extensible cells, andwherein actuating the actuator comprises causing the one or moreextensible cells to act as a fulcrum altering the curvature of theflexible transparent layer.
 20. The method of claim 19, wherein thefirst and the second liquids are provided with indices of refractionthat are substantially equal.
 21. The method of claim 20, wherein theactuator is provided with a third index of refraction that issubstantially equal to the first and second indices of refraction. 22.The method of claim 12, wherein providing the housing further comprisesproviding the housing with a posterior lens.